The field of art to which this invention relates is surgical fastening devices, in particular, surgical fastening devices for fixating tissue grafts to bone.
The medical technology associated with tissue engineering has advanced at a rapid pace. In particular, it is now known to harvest cells from the human body, for example, chondrocytes and fibrochrondrocytes from the knee joint. These autologous cells are then cultured in a laboratory environment on a bioabsorbable matrix. The matrix will typically have a shape substantially similar to the tissue section which needs to be replaced. After a sufficient period of time in an appropriate culture medium at the proper environmental conditions, the harvested cells will grow on the matrix to form an implantable section of tissue having substantially the same physical configuration as the section of tissue which needs to be replaced in the patient. Such a tissue-engineered construct, consisting of cells on the matrix (or, alternatively, consisting of a matrix alone without cells), is then affixed to the bone site using conventionally known surgical fasteners including sutures, periosteal coverings, or fibrin glue.
The advantages of tissue engineering are many, not the least of which is, for example, that it is now possible to replace cartilage with living cartilage tissue. In addition, the likelihood of rejection of the tissue implant is minimized since the cartilage tissue which has been grown in-vitro is identical to the autologous cartilage of the patient.
Although existing matrix fixation devices are adequate for their intended use, there are also some disadvantages attendant with their use. First of all these fixation devices are generic in the sense that they are not specifically designed for matrix fixation to bone or soft tissue, but can be used for a variety of surgical procedures. Other disadvantages include the difficulty in using many of these devices in a minimally invasive arthroscopic procedure. Additional disadvantages include the difficulty and surgical challenge of harvesting a piece of periosteum for use as a periosteal flap, the significant patient morbidity associated with such harvesting, and the difficulty in suturing such a thin, compliant material to surrounding tissue.
Accordingly, there is a need in this art for novel fixation devices that will effectively affix a matrix of tissue-engineered tissue to a bone or other anchoring site so that the tissue may continue to grow and regenerate in the patient""s body.
Therefore, it is an object of the present invention to provide a fixation device that effectively fixates a tissue-engineered matrix to a bone or other anchoring site, thereby enabling the implanted matrix to remain in place while the tissue continues to grow and regenerate.
It is a further object of the present invention to provide such a device for fixating a matrix to a bone site which is easily installed using an arthroscopic procedure or an open procedure.
It is yet a further object of the present invention to provide such a device for fixating a matrix to a bone site which does not require sutures or suture knot tying.
It is still yet a further object of the present invention to provide a surgical method for fixating a matrix utilizing such a device in a location within a patient""s body.
Accordingly, a graft fixation device is disclosed. The graft fixation device has first and second implantation members. The members are elongated and preferably have a cylindrical configuration. The members also have distal ends, proximal ends, and longitudinal axes. There are longitudinal passages extending through the entire length of each implantation member. The members have outer surfaces. The implantation members are connected to each other by a rod member having first and second ends and a central section. The first end of the rod member extends from the proximal end of the first implantation member and the second end of the rod member extends from the proximal end of the second implantation member. The rod member is preferably relatively rigid and may be configured to have a variety of geometric shapes, for example, an inverted xe2x80x9cUxe2x80x9d shape. However, the rod member may also be flexible. The rod member maintains the implantation members at a relatively fixed distance from each other. The central section of the rod member is designed to engage a section of a tissue-engineered matrix implant. In a preferred embodiment, the implantation members have a series of ridges extending out from the outer surfaces of the implantation members to assist in preventing withdrawal from a bone site or other anchoring site after the implantation members are implanted into previously-created bore holes.
Yet another aspect of the present invention is a method of using the graft fixation device of the present invention to affix a matrix containing tissue-engineered tissue to a bone.
Still yet another aspect of the present invention is a graft fixation device combination which is the combination of a fixation device and an insertion member. The fixation device has a first implantation member. The implantation member has a longitudinal axis, a proximal end, a distal end, an outer surface, and a longitudinal passage therethrough. The fixation device also has a second implantation member. The second implantation member has a longitudinal axis, a proximal end, a distal end, an outer surface, and a longitudinal passage therethrough. Each implantation member has a proximal annular face on its proximal end surrounding the longitudinal passages. There is a connecting member connecting the first and second implantation members. The connecting member has a central section, a first end extending from the first implantation member and a second end extending from the second implantation member. There are a pair of insertion devices. Each insertion device is a member having a proximal end, a distal tapered end and a longitudinal passage therethrough. The distal end of each implantation member is in engagement with the proximal end of an insertion device.
Yet another aspect of the present invention is an insertion instrument for inserting the fixation devices and combinations of the present invention in bone. The instrument has a removable distal end housing and removable prongs. The instrument has an elongated member having a proximal end, a distal end, a distal end surface, and an outer surface. Outer screw threads extend out from the outer surface about the distal end. There is a hollow member having a cavity, a proximal end and a distal end, and an outer surface and an inner surface, said hollow member having an opening in the proximal end in communication with the hollow cavity. Inner screw threads extend out from the inner surface of the hollow member. A pair of spaced apart prong holes extend through the distal end of the hollow member, said prong holes being in communication with the cavity. A retention groove extends into the inner surface of the distal end of the hollow member There are a pair of prongs, said prongs having elongated members having distal ends and proximal ends. In a preferred embodiment, a piercing point extending distally from the distal end of each prong. A retention member is mounted to the proximal end of each prong, and the retention member has a proximal surface. The instrument is assembled by inserting the prongs through the prong holes, such that the prongs extend through the prong holes, and the proximal retention members are contained within the retention groove. The hollow member is then screwed onto the distal end of the elongated member, by engaging the mating inner threads with the outer threads, and rotating the hollow member until the distal end surface of the elongated member is in engagement with the proximal surfaces of the retention members.
Still yet another aspect of the present invention is the combination of the insertion instrument as described above and a graft fixation device and combination of the present invention.
These and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.